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Finding the Fourth Proportional to 1,021.12, 1,408.39 and 647.78

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Solution

The fourth proportional to 1,021.12, 1,408.39 and 647.78 is: 893.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,021.12 : 1,408.39 = 647.78 : x
  2. Step 2: Convert to fraction form
    1,021.12/1,408.39 = 647.78/x
  3. Step 3: Cross multiply
    1,021.12x = 1,408.39 × 647.78
  4. Step 4: Simplify right side
    1,021.12x = 912,318.21
  5. Step 5: Solve for x
    x = 912,318.21/1,021.12
  6. Step 6: Final answer
    x = 893.45

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.